21311131302221 has 4 divisors (see below), whose sum is σ = 21319769785152. Its totient is φ = 21302492819292.

The previous prime is 21311131302203. The next prime is 21311131302233. The reversal of 21311131302221 is 12220313111312.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21311131302221 - 2¹⁸ = 21311131040077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311131302521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4319237765 + ... + 4319242698.

It is an arithmetic number, because the mean of its divisors is an integer number (5329942446288).

Almost surely, 2^{21311131302221} is an apocalyptic number.

It is an amenable number.

21311131302221 is a deficient number, since it is larger than the sum of its proper divisors (8638482931).

21311131302221 is an equidigital number, since it uses as much as digits as its factorization.

21311131302221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8638482930.

The product of its (nonzero) digits is 432, while the sum is 23.

Adding to 21311131302221 its reverse (12220313111312), we get a palindrome (33531444413533).

The spelling of 21311131302221 in words is "twenty-one trillion, three hundred eleven billion, one hundred thirty-one million, three hundred two thousand, two hundred twenty-one".